Vehicle purchasers and owners are often aware of the noise the vehicle door makes when it closes. Many people equate the quality and tone of this sound with the quality of the vehicle, and at least one vehicle manufacturer has even used this sound in its advertising.
More expensive vehicles have vehicle doors made from thicker, heavier metal. As a result, the sound made by these doors when closed tend to have low frequency content with no reverberations. Doors on less expensive vehicles, by contrast, create a noise having higher frequency content and multiple reverberations when closed. The lower frequency noise can be described as a “thunk,” while the higher frequency noise can be described as “tinny.” The impressions formed by these various noises is intuitive and is often made without any conscious effort by the listener.
Because the sound of the vehicle door closing is so important in creating a favorable user impression of the vehicle, there is a desire for a system that can control and modify the noise of the vehicle door when it closes.